https://en.wikipedia.org/wiki/Historian

Systematic historical thought emerged in ancient Greece, a development that became an important influence on the writing of history elsewhere around the Mediterranean region. The earliest known critical historical works were The Histories, composed by Herodotus of Halicarnassus (484 – c. 425 BCE) who later became known as the "father of history" (Cicero).

Now how many people had access to this knowledge is another matter, but studying history and learning from it was an important aspect in the education and training of leaders to be since more than a thousand years at the very least.

If we look at Moses and the Pharaoh as well as ancient Greek democracies, we can conclude that the principles of politics have not changed all that much in the past 3000-4000 years of human history. The knowledge was always there and the same mistakes are always repeated, with some very incremental progresses and regressions in between.

They so often did though, how many massive fires broke out in London before the great fire finally convinced them to stop building overlapping thatched rooves.

Even during The Plague of Justinian scholars wrote about what was essentially ancient social distancing practices, 2000 years ago later we still can't do it properly.

How many times did they have to put up with rat plagues and stinking open cess pits, followed by a big town clean up, and then nothing change in infrastructure or waste management practices, only to do the whole clean up again ....until the Great Stink got to close enough to the windows of parliament that those in power decided maybe they should address the root problem instead of applying bandaids every few years.

(I don't have a history degree so I'm pulling these details out of the memory depths of my dusty documentary viewings, and I'm probably wrong.)

I’m sure they had some knowledge. It’s just that the priests foretold victory in the course chosen by the leaders, the gods are with them! So off they go to war and conquest or whatever.